Buttress Retention System for Linear Endostaplers

ABSTRACT

An end effector for use with a surgical stapler comprising a staple cartridge having a tissue contacting surface, a first side surface, and a second side surface opposite the first side surface, an anvil plate having a tissue contacting surface, a first side surface, and a second side surface opposite the first side surface, wherein the first and second side surfaces of each of the staple cartridge and anvil plate have overmolded zones, a buttress releasably disposed on the tissue contacting surfaces of each of the staple cartridge and the anvil plate, and a pair of sutures wherein each suture is bonded to the respective overmolded zones of the first and second side surfaces configured to retain the respective buttress atop the respective tissue contacting surfaces.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical stapling apparatus and, more particularly, to a surgical stapling apparatus including an anchor member or members affixed to at least one of an anvil plate and staple cartridge to secure one or more buttresses thereto.

2. Background of Related Art

Surgical stapling instruments that are used to sequentially or simultaneously apply one or more rows of fasteners to join segments of body tissues are well known in the art. The fasteners are typically in the form of surgical staples but two part polymeric fasteners can also be utilized. Such devices generally include a pair of jaws to clamp the body tissues between such jaws. Typically, one of the jaw members includes a staple cartridge which accommodates a plurality of staples arranged in one or more rows while the other jaw member has an anvil plate that defines a surface for forming the staple legs as the staples are driven from the staple cartridge against the anvil.

Certain surgical staplers have elongate jaws that apply linear rows of staples to tissue. When such a stapling instrument is actuated, a longitudinally translating actuation member contacts staple drive members in one of the jaws which in turn acts upon staple pushers to sequentially eject the staples from the staple cartridge. For example, longitudinally traveling cam bar members can be used to interact with the staple drive members. Alternatively, the staples can be driven simultaneously. A blade can travel between the staple rows to longitudinally cut and/or open the stapled tissue between the rows of staples. Such instruments are disclosed, for example, in U.S. Pat. No. 3,079,606 and U.S. Pat. No. 3,490,675.

When stapling relatively thin or fragile tissues, it may be important to effectively seal the staple line against air or fluid leakage. Additionally, it may be necessary to reinforce the staple line against the tissue to prevent tears in the tissue or pulling of the staples through the tissue. One method of preventing tears or pull through involves the placement of a biocompatible fabric reinforcing material, or a “buttress,” between the staple and the underlying tissue. In this method, a layer of buttress is placed against the tissue and the tissue is stapled in a conventional manner. Surgical staplers utilizing pins or clips to temporarily connect buttresses to each of the jaws of the staplers, i.e., one disposed on the staple cartridge and the other on the anvil plate, are known.

The present application discloses a retention system for securing one or more buttresses to the jaws of the stapler. The retention system allows the buttresses to be secured to a tissue contacting surface of the staple cartridge and anvil plate. This retention system reduces manufacturing costs associated with surgical staplers. Further, this retention system diminishes the likelihood of premature suture release during assembly, packing or firing. Fewer design and testing constraints will be imposed as less precision is required to achieve acceptable functioning retention elements.

SUMMARY

The present application discloses an end effector for use with a surgical stapler, the end effector comprising a staple cartridge assembly having a tissue contacting surface, a first side surface, and a second side surface opposite the first side surface, an anvil assembly having a tissue contacting surface, a first side surface, and a second side surface opposite the first side surface, the staple cartridge assembly and anvil assembly having proximal and distal attachment zones. A buttress is releasably disposed on the tissue contacting surfaces of each of the staple cartridge assembly and anvil assembly, and a pair of anchor members are affixed to the attachment zones of each of the staple cartridge assembly and anvil assembly and are configured to retain the respective buttress material atop the respective tissue contacting surfaces. In certain embodiments, one of the staple cartridge assembly and anvil assembly has a buttress material releasably attached thereto.

In certain embodiments, the first and second side surfaces of each of the staple cartridge assembly and anvil assembly have overmolded zones, a buttress releasably disposed on the tissue contacting surfaces of each of the staple cartridge and the anvil plate, and a pair of anchor members wherein each anchor member is bonded to the respective overmolded zones of the first and second side surfaces configured to retain the respective buttress atop the respective tissue contacting surfaces. Preferably, the overmolded zones are made from polymeric material. Alternatively, attachment zones may be composed of press fit parts that are attached to the anvil assembly, or attachment zones may be composed of molded features integral to the cartridge assembly. The anchor member is desirably a polymeric suture. A proximal suture is positioned along a proximal portion of each of the staple cartridge assembly and anvil assembly, and a distal suture is positioned along a distal portion of each of the staple cartridge assembly and the anvil assembly. A first end of the proximal suture couples to the overmolded zone of the first side surface and a second end of the proximal suture couples to the overmolded zone of the second side surface. The proximal suture passes transversely across a proximal portion of the buttresses of each of the staple cartridge assembly and anvil assembly. Similarly, a first end of the distal suture couples to the overmolded zone of the first side surface and a second end of the distal suture couples to the overmolded zone of the second side surface. The distal suture passes transversely across the distal portion of the buttresses of each of the staple cartridge assembly and anvil assembly.

The staple cartridge assembly and the anvil assembly have a central longitudinal slot configured to enable a passage of a knife blade therethrough. The proximal suture is positioned distally from a proximal end of the central longitudinal slot on each of the staple cartridge assembly and anvil assembly. The distal suture is positioned proximally from a distal end of the central longitudinal slot on each of the staple cartridge assembly and anvil assembly.

In a further aspect, an end effector for use with a surgical stapler, the end effector comprising: a staple cartridge having a tissue contacting surface, a first side surface and a second side surface opposite the first side surface, wherein the first and second side surfaces have overmolded zones disposed near a proximal and distal portion thereof and an anvil plate having a tissue contacting surface, a first side surface and a second side surface opposite the first side surface, wherein the first and second side surfaces have overmolded zones disposed near a proximal and distal portion thereof. A buttress material is releasably disposed on the tissue contacting surfaces of each of the staple cartridge and the anvil plate. The end effector has a pair of sutures, wherein each suture is bonded to the respective overmolded zones of the first and second side surfaces of each of the staple cartridge and anvil plate.

A proximal suture may be positioned along the proximal portion of each of the staple cartridge and anvil plate, and a distal suture may be positioned along the distal portion of each of the staple cartridge and the anvil plate. A first end of the proximal suture may couple to the overmolded zone of the first side surface and a second end of the proximal suture may couple to the overmolded zone of the second side surface such that the proximal suture passes transversely across a proximal portion of the buttresses of each of the staple cartridge and anvil plate. A first end of the distal suture may couple to the overmolded zone of the first side surface and a second end of the distal suture may couple to the overmolded zone of the second side surface such that the distal suture passes transversely across the distal portion of the buttresses of each of the staple cartridge and anvil plate.

In certain embodiments, the staple cartridge and the anvil plate have a central longitudinal slot configured to enable passage of a knife blade therethrough. The proximal suture may be positioned distally from a proximal end of the central longitudinal slot on each of the staple cartridge and anvil plate.

The distal suture may be positioned proximally to a distal end of the central longitudinal slot on each of the staple cartridge and anvil plate.

DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed interlocking buttress retention systems are disclosed herein with reference to the drawings, wherein:

FIG. 1 is a perspective view of a surgical stapling apparatus according to an embodiment of the present disclosure;

FIG. 2 is a top, exploded, perspective view of a distal end of the surgical stapling apparatus of FIG. 1;

FIG. 3 is a perspective view of a cartridge assembly of FIG. 2, illustrating a cartridge buttress material secured thereto;

FIG. 4 is a perspective view of an anvil assembly of FIG. 2, illustrating an anvil buttress material secured thereto; and

FIG. 5 is a perspective view of a cartridge assembly and an anvil assembly, illustrating sutures affixed thereto.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed buttress retention method for linear endostaplers will now be described in detail with reference to the drawings wherein like numerals designate identical or corresponding elements in each of the several views. As is common in the art, the term ‘proximal” refers to that part or component closer to the user or operator, i.e. surgeon or physician, while the term “distal” refers to that part or component further away from the user.

Referring now to FIG. 1, there is disclosed a linear surgical stapling instrument or surgical stapler 10 for use in stapling tissue and applying layers of buttress material between the staples and underlying tissue. An exemplary example of this type of surgical stapling instrument is disclosed in U.S. Pat. No. 7,128,253, the entire disclosure of which is incorporated by reference herein.

Surgical stapler 10 generally includes a handle 12 having an elongate tubular member 14 extending distally from handle 12. An end effector 100 is secured on the distal end of elongate tubular member 14. End effector 100 includes a cartridge assembly 200 housing a plurality of surgical fasteners or staples 223 (see FIG. 2) and an anvil assembly 300 movably secured in relation to cartridge assembly 200. Handle assembly 12 includes a stationary handle member 22, a movable handle member 24, and a barrel portion 26. An articulation lever 30 is mounted on the forward end of barrel portion 26 adjacent rotatable member 28 to facilitate articulation of end effector 100. A pair of knobs 32 are movably positioned along barrel portion 26. Knobs 32 are advanced distally to approximate or close cartridge and/or anvil assembly 200, 300, and retracted proximally to unapproximate or open cartridge and/or anvil assembly 200, 300. Actuation of movable handle member 24 applies lines of staples 223 to tissue. In order to properly orient cartridge and anvil assembly 200, 300 relative to the tissue to be stapled, surgical stapling apparatus 10 is additionally provided with a rotatable member 28 on the forward end of barrel portion 26. Rotation of rotatable member 28 relative to handle assembly 12 rotates elongate body 14 and loading unit 100 relative to handle assembly 12 so as to properly orient cartridge assembly 200 and anvil assembly 300 relative to the tissue to be stapled.

One or more buttresses are attached to the cartridge assembly, the anvil assembly, or both. For example, the cartridge assembly 200 is provided with a cartridge buttress 500 a and anvil assembly 300 is provided with an anvil buttress 500 b in the manners described in more detail hereinbelow. A cartridge buttress retention system 250 (see FIG. 3) is provided to releasably secure cartridge buttress 500 a to staple cartridge assembly 200. Likewise, an anvil buttress retention system 340 (see FIG. 4) is provided to releasably secure anvil buttress 500 b to anvil assembly 300. Cartridge buttress 500 a and anvil buttress 500 b and are provided to reinforce and seal staple lines applied to tissue by surgical stapler 10.

The buttresses 500 a, 500 b may be made from any biocompatible natural or synthetic material. The material from which the buttresses 500 a, 500 b are formed may be bioabsorbable or non-bioabsorbable. It should be understood that any combination of natural, synthetic, bioabsorbable and non-bioabsorbable materials may be used to form the buttress material. The buttresses 500 a, 500 b may be porous or non-porous, combination of porous and non-porous layers. The non-porous buttresses 500 a, 500 b may be utilized to retard or prevent tissue ingrowth from surrounding tissues thereby acting as an adhesion barrier and preventing the formation of unwanted scar tissue. The buttress materials may be provided in the form of a sheet, a non-woven material, felt, mesh, foam or other form.

Additional exemplary materials for surgical buttresses 500 a, 500 b for use with the surgical stapling devices disclosed herein are set forth in commonly assigned U.S. Pat. Nos. 5,542,594; 5,908,427; 5,964,774; and 6,045,560, and commonly assigned U.S. Application Publication Nos. 2006/0085034, filed on Apr. 20, 2006; and 2006/0135992, filed on Jun. 22, 2006, the entire contents of each of which is incorporated herein by reference. Bio-absorbable polymers, non-bioabsorbable polymers, biologically appropriate metals, tissue-derived materials and composites thereof may be used.

As seen in FIG. 2, cartridge assembly 200 includes a carrier 210 defining an elongated support channel 212. Elongated support channel 212 of carrier 210 is dimensioned and configured to selectively receive a staple cartridge 220 therein. Staple cartridge 220 includes retention slots 222 formed therein for receiving a plurality of fasteners 223 and pushers 226. A central longitudinal slot 234 is formed in and extends along the length of staple cartridge 220 to facilitate passage of knife blade 156 of drive bar 150 therethrough. During operation of surgical stapler 10, actuation sled 228 translates through staple cartridge 220 to advance the cam wedges into sequential contact with pushers 226, to cause pushers 226 to translate vertically within retention slots 222 and urge staples 223 from slots 222 into staple forming cavities of anvil plate 310 of anvil assembly 300.

Cartridge buttress 500 a of cartridge assembly 200 is operatively and releasably secured to a tissue contacting surface of staple cartridge 220, by cartridge buttress retention system 250 wherein anchor members, which may comprise sutures “S1, S2,” overlie the tissue contacting surface of the staple cartridge. In certain embodiments, the sutures overlie retention slots 222 and/or at least a portion of a length of longitudinal slot 234. A first anchor member or suture “S1” is affixed, as described in further detail hereinbelow, to staple cartridge 220 of the cartridge assembly and around/over distal portion of cartridge buttress 500 a, and a second anchor member or suture “S2” is affixed to staple cartridge 220 around/over proximal portion of cartridge buttress 500 a. Other anchor members may be used, such as straps, sheets, wires, cables, threads, rods, etc.

As best seen in FIG. 3, cartridge assembly 200 is shown with cartridge buttress 500 a affixed by cartridge buttress retention system 250. Cartridge buttress 500 a is positioned on the tissue contacting surface of staple cartridge 220. A first end of each anchor member or suture “S1, S2” is anchored or fixed to the staple cartridge assembly, and the second end of each suture is anchored or fixed to a second side surface of the staple cartridge assembly at attachment zones. For example, the first side surface 240 and second side surface of staple cartridge 220 have respective distal and proximal overmolded zones 242 a, 244 a, provided near the distal and proximal portions of staple cartridge 220. A second end of each suture “S1, S2” passes transversely across respective distal and proximal portions of cartridge buttress 500 a and is anchored or fixed to a second side surface 246, opposite first side surface 240, at respective distal and proximal overmolded zones 242 b, 244 b, provided near the distal and proximal portions of staple cartridge 220. In this manner, sutures “S1, S2” are bonded to the overmolded zones and thus secure cartridge buttress 500 a underneath to the tissue contacting surface of staple cartridge 220.

With reference again to FIG. 2, anvil assembly 300 includes an anvil plate 310 having a plurality of staple deforming pockets/cavities 310 a (see FIG. 4) and a cover plate 320 secured to a top surface of anvil plate 310. Anvil assembly 300 further includes a knife blade 330 operatively interposed within the cavity defined between anvil plate 310 and cover plate 320.

Similar to cartridge buttress 500 a, anvil buttress 500 b may be operatively secured to a tissue contacting surface of anvil plate 310, by anvil buttress retention system 340. For example, sutures “S3, S4,” overlie anvil pockets 310 a and/or at least a portion of a length of longitudinal slot 314. A third suture “S3” is affixed to the anvil plate 310 around/over distal portion of anvil buttress 500 b, and a fourth suture “S4” is affixed to anvil plate 310 around/over proximal portion of anvil buttress 500 b.

As shown in FIG. 4, anvil assembly 300 is shown with anvil buttress 500 b affixed by anvil buttress retention system 340. Anvil buttress 500 b is positioned on the tissue contacting surface of anvil plate 310. A first end of each suture “S3, S4” is anchored or fixed to a first side surface 330 of anvil plate 310 extending from the tissue contacting surface, at respective distal and proximal overmolded zones 332 a, 334 a, provided near the distal and proximal portions of anvil plate 310. A second end of each suture “S3, S4” passes transversely across respective distal and proximal portions of anvil buttress 500 b and is anchored or fixed to a second side surface 336, opposite first side surface 330, at respective distal and proximal overmolded zones 332 b, 334 b, provided near the distal and proximal portions of anvil plate 310. In this manner, sutures “S3, S4 are bonded to the overmolded zones and thus secure anvil buttress 500 b underneath to the tissue contacting surface of anvil plate 310.

Bonding between the sutures and the overmolded zones of the cartridge buttress retention system and the anvil buttress retention system may be achieved by ultrasonic welding, laser welding, solvent welding, heat pressing, or by other similar methods known in the art of plastic to plastic bonding. It is contemplated that the overmolded zones are made of biocompatible plastic to which the sutures may optimally bond by the chosen bonding method. The overmolded plastic zones may be textured or grooved to accept the sutures and to promote optimal bonding. Alternatively, attachment zones may be composed of press fit parts that are attached to the anvil assembly, or attachment zones may be composed of molded features integral to the cartridge assembly.

Cartridge and anvil buttresses 500 are shown having a uniform profile. An example of this type of buttress is disclosed in U.S. Patent Publication No. 2011/0089220 filed on May 21, 2011, the entire disclosure of which is incorporated by reference herein. The buttresses include a head portion 510, a body portion 520, and a neck portion 530 interconnecting head portion and body portion. Body portion 520 defines a pair of opposing distal recesses 524 on transverse edges near a distal portion thereof. The pair of opposing distal recesses 524 are utilized to secure the body portion to a distal portion of each of the anvil plate and the staple cartridge.

Similarly, body portion 520 further defines a two pairs of opposing proximal recesses 526 a, 526 b on transverse edges near a proximal portion thereof. The pair of proximal recesses 526, 526 b secure the body portion to a proximal portion of each of the anvil plate and the staple cartridge. The two pairs of proximal recesses allow the buttresses to accommodate various types of profiles of the anvil and cartridge assemblies. While the buttresses have been shown herein having a specific shape and design, it will be appreciated by those skilled in the art, that the buttresses may have various shapes to secure to the tissue contacting surfaces of various anvil and cartridge assemblies.

In operation, with end effector 100 coupled to a distal end of elongated body 14 of surgical stapling apparatus 10, and with cartridge and anvil buttresses 500 a, 500 b pre-loaded onto cartridge assembly 200 and anvil assembly 300, respectively, surgical stapling apparatus 10 is used in accordance with methods known by those skilled in the art. Once cartridge assembly 200 and anvil assembly 300 are clamped onto tissue, surgical stapling apparatus 10 is fired. In firing surgical stapling apparatus 10, drive bar 150 is advanced from a proximal-most position to a distal-most position of end effector 100. In so doing, knife blade 156 of drive bar 150 enters notch 528 of buttresses 500 a, 500 b thereby facilitating the dividing of buttresses 500 a, 500 b and reducing any incidents of pushing or bunching-up of buttresses 500 a, 500 b by blade 156. As drive bar 150 begins to travel distally, knife blade 156 substantially simultaneously cuts through a central section of the proximal sutures “S2, S4” of cartridge assembly 200 and anvil assembly 300, thereby respectively freeing the proximal ends of cartridge and anvil buttresses 500 a, 500 b therefrom. As knife blade 156 is moved distally, knife blade 156 slices or cuts longitudinally through both cartridge buttress 500 a and anvil buttress 500 b, thereby dividing the buttresses 500 a, 500 b substantially in half.

Additionally, as drive bar 150 approaches the distal-most position, drive bar 150 and/or knife blade 156 engage sutures “S1, S3” and sever distal sutures “S1 or S3” and thus release a distal end of buttresses 500 a, 500 b. In certain embodiments, a separate blade is mounted in the staple cartridge assembly and/or anvil assembly for cutting the anchor member or suture.

Referring to FIG. 5, staple cartridge 220 and anvil plate 310 are shown with the respective sutures affixed thereto without the buttresses. The sutures of cartridge assembly 200 and anvil assembly 300 are selectively positioned such that proximal sutures “S2, S4” are located distally from a proximal end of longitudinal slots 234, 314. Similarly, distal sutures “S1, S3” are located proximally from a distal end of longitudinal slots 234, 314. This allows knife blade 156 (FIG. 2) to sever proximal sutures “S2, S4” and distal sutures “S1, S3” as knife blade 156 translates along longitudinal slots 234, 314.

In certain other embodiments, the anchor member is welded, glued, or otherwise attached to the staple cartridge assembly and/or anvil assembly without the use of the overmolded material. For instance, attachment zones may be composed of press fit parts that are attached to the anvil assembly, or attachment zones may be composed of molded features integral to the cartridge assembly. In addition, in any of the embodiments discussed herein, the anchor member or members are permanently attached to the staple cartridge assembly and/or anvil assembly. However, in any of the embodiments disclosed herein, the anchor member or members can be temporarily attached to the staple cartridge assembly and/or anvil assembly so as to allow the anchor member to separate from the end effector to allow the buttress material to be released.

It will be understood that various modifications may be made to the embodiments of the presently disclosed buttress retention system for linear endostaplers. For example, the disclosed retention system is not limited to a stapling apparatus but may find application in other instruments and situations requiring material to be releasably retained on the surface of a surgical instrument. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure. 

What is claimed is:
 1. An end effector for use with a surgical stapler, the end effector comprising: a staple cartridge assembly having a tissue contacting surface, a first side surface extending from the tissue contacting surface, and a second side surface opposite the first side surface; an anvil assembly having a tissue contacting surface, a first side surface extending from the tissue contacting surface, and a second side surface opposite the first side surface; the staple cartridge assembly and anvil assembly having proximal and distal attachment zones; a buttress releasably disposed on the tissue contacting surfaces of each of the staple cartridge and the anvil plate; and a pair of anchor members affixed to the attachment zones of each of the staple cartridge and anvil plate configured to retain the respective buttress material atop the respective tissue contacting surfaces.
 2. The end effector of claim 1, wherein the first and second side surfaces of each of the staple cartridge assembly and anvil assembly have overmolded zones, wherein each anchor member is bonded to the respective overmolded zones of the first and second side surfaces.
 3. The end effector of claim 2, wherein the overmolded zones are made from a polymeric material.
 4. The end effector of claim 2, wherein a proximal suture is positioned along a proximal portion of each of the staple cartridge assembly and anvil assembly, and a distal suture is positioned along a distal portion of each of the staple cartridge assembly and the anvil assembly.
 5. The end effector of claim 4, wherein the anchor member comprises a polymeric suture.
 6. The end effector of claim 5, wherein a first end of the proximal suture couples to the overmolded zone of the first side surface and a second end of the proximal suture couples to the overmolded zone of the second side surface such that the proximal suture passes transversely across a proximal portion of the buttresses of each of the staple cartridge assembly and anvil assembly, wherein a first end of the distal suture couples to the overmolded zone of the first side surface and a second end of the distal suture couples to the overmolded zone of the second side surface such that the distal suture passes transversely across the distal portion of the buttresses of each of the staple cartridge assembly and anvil assembly.
 7. The end effector of claim 6, wherein the staple cartridge assembly and the anvil assembly have a central longitudinal slot configured to enable a passage of a knife blade therethrough.
 8. The end effector of claim 7, wherein the proximal suture is positioned distally from a proximal end of the central longitudinal slot on each of the staple cartridge assembly and anvil assembly.
 9. The end effector of claim 8, wherein the distal suture is positioned proximally from a distal end of the central longitudinal slot on each of the staple cartridge assembly and anvil assembly.
 10. An end effector for use with a surgical stapler, the end effector comprising: a staple cartridge having a tissue contacting surface, a first side surface and a second side surface opposite the first side surface, wherein the first and second side surfaces have overmolded zones disposed near a proximal and distal portion thereof; an anvil plate having a tissue contacting surface, a first side surface and a second side surface opposite the first side surface, wherein the first and second side surfaces have overmolded zones disposed near a proximal and distal portion thereof; a buttress material releasably disposed on the tissue contacting surfaces of each of the staple cartridge and the anvil plate; and a pair of sutures, wherein each suture is bonded to the respective overmolded zones of the first and second side surfaces of each of the staple cartridge and anvil plate.
 11. The end effector of claim 10, wherein a proximal suture is positioned along the proximal portion of each of the staple cartridge and anvil plate, and a distal suture is positioned along the distal portion of each of the staple cartridge and the anvil plate.
 12. The end effector of claim 11, wherein a first end of the proximal suture couples to the overmolded zone of the first side surface and a second end of the proximal suture couples to the overmolded zone of the second side surface such that the proximal suture passes transversely across a proximal portion of the buttresses of each of the staple cartridge and anvil plate, wherein a first end of the distal suture couples to the overmolded zone of the first side surface and a second end of the distal suture couples to the overmolded zone of the second side surface such that the distal suture passes transversely across the distal portion of the buttresses of each of the staple cartridge and anvil plate.
 13. The end effector of claim 12, wherein the staple cartridge and the anvil plate have a central longitudinal slot configured to enable passage of a knife blade therethrough.
 14. The end effector of claim 13, wherein the proximal suture is positioned distally from a proximal end of the central longitudinal slot on each of the staple cartridge and anvil plate.
 15. The end effector of claim 14, wherein the distal suture is positioned proximally for a distal end of the central longitudinal slot on each of the staple cartridge and anvil plate. 